Towards Achieving Net-zero Emissions from the Co-combustion of Natural Gas and Biomass: A Commercial Pathway for Evaluating the Performance of a Novel Solvent Blend
The pressing need to reduce greenhouse gas emissions, particularly CO2, necessitates a clean-up of the energy sector. Coal, traditionally valued for its abundance, low cost, and reliability, unfortunately emits significant amounts of CO2 contributing to air pollution, acid rain, and climate change issues. Despite ongoing efforts to transition to cleaner energy sources, the continued use of coal intensifies atmospheric CO2 levels. In 2023, Avor et al. reported on the optimum amount of natural gas and biomass needed to be combusted for the generation of electricity at a relatively lower CO2 emission rate. Through this indirect combustion of natural gas and biomass and post combustion carbon capture, result showed potential of achieving net-zero emission. Extensive research has explored various methods to mitigate the impact of fossil fuel combustion for energy generation, with amine post-combustion technology emerging as the most preferred and cost-effective solution. However, the key challenge lies in identifying an optimal solvent that maximizes CO2 removal efficiency with rapid absorption and desorption kinetics and lower heat duty, as these factors significantly influence operational costs.
To identify a commercially viable solvent for capturing CO2 from flue gas produced by the indirect co-combustion of natural gas and biomass, comparative performance studies was conducted on 5M monoethanolamine (MEA) and a novel solvent (AP) in a pilot-line plant using simulated flue gas. The promising results from our novel solvent, AP during preliminary screenings underscore the need for pilot plant testing to advance towards commercialization. Pilot line testing validated the solvent’s performance on a larger scale and confirmed its economic viability for widespread adoption in CO2 capture technologies, surpassing the benchmark solvent, 5M MEA.
Key performance indices evaluated to describe the absorption-desorption carbon capture process included cyclic capacity, overall mass transfer coefficients, CO2 removal efficiency, and heat duty. Cyclic capacity, defined as the difference between rich and lean loading, significantly impacts solvent circulation rates and operational costs. A higher cyclic capacity translates into a smaller solvent circulation volume, reduced absorber diameter, and lower pump capacity requirements. Additionally, the overall volumetric mass transfer coefficients (KGav and KLav) describe the rate of CO2 absorption and desorption, with higher coefficients enabling faster CO2 capture and optimizing reactor sizing. Heat duty, representing the energy supplied per unit of CO2 produced during desorption, is another crucial performance criterion. While 5M MEA offers rapid initial absorption kinetics and high CO2 removal efficiency, its carbamate formation necessitates higher energy for CO2 stripping. Our novel solvent AP shows comparable absorption capabilities to 5M MEA while demonstrating superior desorption performance, highlighting its potential for enhanced efficiency, reduced energy requirement for solvent regeneration, thus reduced operational costs.